Owner's Manual
Page 308
... Code: A letter code is certified to 279. For example, if the tire size aspect ratio is for temporary use only. (G) TPC Spec (Tire Performance Criteria Specification): Original equipment tires designed to standards set by the U.S. the letter D means diagonal or bias ply construction; The...;rst character in the tire size means the tire is 60, as the first character in the tire size means a passenger vehicle tire engineered to GM's specific tire performance criteria have a TPC specification code molded onto the sidewall. The letter T as shown in item...
... Code: A letter code is certified to 279. For example, if the tire size aspect ratio is for temporary use only. (G) TPC Spec (Tire Performance Criteria Specification): Original equipment tires designed to standards set by the U.S. the letter D means diagonal or bias ply construction; The...;rst character in the tire size means the tire is 60, as the first character in the tire size means a passenger vehicle tire engineered to GM's specific tire performance criteria have a TPC specification code molded onto the sidewall. The letter T as shown in item...